Luke Coletti <[EMAIL PROTECTED]> writes: > You still appear to be asserting that in calculating the > Longitude of Perihelion (over a 10,000 year period), only Precession > need be considered and the shifting of Perihelion due to > perturbation and other smaller combined effects can be ignored. I'm > sorry to appear picky, but this assertion is most definitely > incorrect.
You have convinced me that Danny Hillis will indeed have to put a lot of (slowly turning) gears into the Millennium Clock. I am surprised at the size of the change in Eccentricity, but maybe I shouldn't be. The perturbations from the other planets probably affect it in much the same way as they affect the Longitude of Perihelion. Even the change in Obliquity amounts to nearly a minute, and it would be a shame if the people in the year 12000 could not set their watches by the Clock. One thing that threw me is that you quoted 12 arc-sec/yr as the rate of shift of the Perihelion during the period 1980-2020. The numbers you give above for the period 2000 to 12000 amount to 66 arc-sec/yr. Can you explain why the shift is so irregular? Can you explain why the shift exists at all? These questions are getting very deep into celestial mechanics, and I am willing to defer discussion until I have at least read Meeus. Regards, Art Carlson
